A Minimalist Single Axle Trailer Dolly

Very basic, frame rails, tongue, fifth wheel plate and a rear bumper. Nothing extra here, but still some decent scale detail in the fifth wheel plate and frame rails that are strong enough even in PLA.

Tamiya hardware

This design has integrated mounting holes to use a single axle Tamiya suspension setup. You will need some spacers from the Tamiya kit (I've attached instructions illustrating those as well as the plastic adapters to put a single axle in the middle o the leaf spring (also added photos for that). These are on the "C" tree for most Tamiya trucks I think. There are options on thingiverse for printing some of these parts as well. The other parts that come from Tamiya kits are the fifth wheel itself, associated mounting hardware and the release mechanism. You can also obtain the rectangle taillight lenses from the flatbed kit and mudflaps or make your own.

Additional hardware needed

The front tongue is held on by 4mm battery bullet connectors and you'll need a few extra 3mm screws (the same as used in all Tamiya kits) to put the rest of it together. The rear bumper and the top plate use wood style threads and thread right into the rails. All other fasteners have a recessed hole for a flanged lock nut also used in Tamiya kits. A few spacers for the leaf spring to frame rail mount are included to print.

The tongue

The tongue is currently designed to leverage the rc4wd pintle hook mount. Its not the cheapest, but is pretty good looking and I think accurate for the style used in the US. The tongue is a fixed position and does not hinge from the frame rails.

With that said, its fairly trivial to adapt the design to a different type of mount like a rod end. If you want a specific type of mount, post in the comments and I'll do my best to provide it and add it to the make, or you can load up that .stl into tinkercad and make it for yourself.

NOTE: The framerails are identical mirrors of each other. Simply mirror the one provided to get the other.

Feedback is welcome, happy making!